1. Field of the Invention
The present invention relates generally to a process for attaching and removing a flip chip configured or other conductively bumped semiconductor die by way of an electrically resistive thermal supply circuit used to provide heat to melt an electrical connection material forming bonds between the semiconductor die and a substrate. Also, the invention relates to forming modules having a plurality of semiconductor dice, commonly referred to as multi-chip modules (MCMs), wherein at least one semiconductor die is flip chip configured or otherwise conductively bumped so that mechanical and electrical bonds with a carrier substrate may be created or eliminated by way of a thermal supply circuit that supplies heat either directly or indirectly to a solder ball, solder paste, electrically conductive or conductor-filled thermoplastic, or other suitable electrical connection material.
2. State of the Art
In conventional semiconductor device fabrication processes, a number of distinct semiconductor devices, such as memory chips or microprocessors, are fabricated on a semiconductor substrate, such as a silicon wafer or other bulk semiconductor substrate. After fabrication, the devices are typically singulated to separate the individual semiconductor devices from one another. In addition, various post-fabrication processes, such as testing and burn-in processes, may be employed either prior to or following singulation of the semiconductor dice. Further, the individual semiconductor devices, commonly termed “bare dice”, may be packaged in one of a number of configurations. Along with the trend in the semiconductor industry to decrease semiconductor device size and increase the density of structures of semiconductor devices, package sizes are also ever-decreasing. One type of semiconductor device package, the so-called “chip-scale package” or “chip-sized package” (“CSP”), consumes about the same amount of area or “real estate” upon a carrier substrate, such as a circuit board to which the CSP is mounted, as the bare semiconductor die itself. Such chip-scale packages may include an interposer substrate having roughly the same surface area as the semiconductor device and used to redistribute input/output or “I/O” connections from the semiconductor die to a configuration more suitable for connection to higher-level packaging.
A particular type of CSP and substrate connection, commonly referred to as a flip chip, has enjoyed some success. A chip having conductive bumps of, for example, solder arranged on the active surface thereof is aligned to the carrier substrate with the conductive bumps in contact with terminal pads of the carrier substrate, and all connections are made simultaneously by heating and reflowing the solder. It is also known to employ conductive bumps of a conductive or conductor-filled polymer or epoxy in lieu of solder bumps.
Although the flip chip has been a popular configuration for semiconductor devices, the densification of die and substrate interconnections, as well as technological advances in the art, have decreased the overall size of the semiconductor die (for a given circuit density) and, thus, requires constant redesign, reduces bond pad size and pitch (spacing) and may also result in die-to-carrier substrate compatibility issues. Further, due to ongoing advances in circuit component design and fabrication technology, a given die may be “shrunk” one or more times during its commercial lifespan to enhance per-wafer yield, device speed and performance, and quality, such “shrinks” often resulting in bond pad relocation. Consequently, the need to enable varying sized semiconductor dice and/or changing bond pad arrangements to be compatible with a given substrate has been recognized.
In response, flip chip integrated circuit (IC) designs may employ a redistribution layer to enable varying sized semiconductor dice and/or changing bond pad arrangements to be compatible with a terminal pad arrangement of a given substrate. The redistribution layer is a layer that is formed over an active surface of a flip chip IC to enable electrical interconnection to a particular package via solder or other conductive bumps. The redistribution layer includes a number of conductive traces that connect a plurality of bond pads on the active surface to rerouted locations of each of the solder or other conductive bumps arranged in an array format, usually more widely pitched. Therefore, redistribution layers may be modified as a part of the semiconductor die fabrication process at the wafer level to enable changing semiconductor die bond pad configurations to be electrically connected to a given substrate, including installation within a MCM. Likewise, redistribution layers may be used to adapt a given semiconductor die bond pad arrangement to different terminal pad arrangements of different carrier substrates. MCM configurations, such as random access memory modules used in personal computers, are commonly formed with multiple memory chips on a single substrate, such as single-in-line memory modules (SIMMs), dual in-line modules (DIMMs), triple in-line memory modules (TRIMMs) and Rambus in-line memory modules (RIMMs).
Once a conductively bumped semiconductor die, including those using a redistribution layer, is connected to a carrier substrate such as an MCM, it becomes difficult to remove or replace the semiconductor die as the electrical connections between the semiconductor die and the carrier substrate are hidden from view and inaccessible. Consequently, replacement methods and apparatus have been developed for replacing a defective component installed upon a carrier substrate such as a printed circuit board (“PCB”). One method used to replace a conductively bumped semiconductor die is to simply mechanically mill the component from the carrier substrate.
A method used to remove electrical components soldered to a carrier substrate is to heat the carrier substrate in an oven to the reflow temperature of the solder of the conductive bumps. Yet another method to remove soldered components is to locally heat the component to reflow temperature using hot air in order to remove it from the carrier substrate. Examples of convection-type heating devices used to remove components soldered to a carrier substrate are disclosed in U.S. Pat. No. 4,426,571 and U.S. Pat. No. 4,799,617. However, hot air flow is difficult to precisely direct and isolate, may cause overheating of semiconductor devices and structures adjacent to the semiconductor devices that are intended to be removed and, due to the large volume and flow of sufficiently hot air that is required to replace a semiconductor device, may also damage the PCB.
In an attempt to eliminate the problems associated with heating semiconductor dice in an oven or utilizing the convection-type rework devices, in some instances heaters have been embedded in or carried by printed circuit boards for use in the soldering of an electronic component to a circuit substrate and in attachment/disassembly operations. Such arrangements are shown in U.S. Pat. No. 5,010,233 and U.S. Pat. No. 5,175,409.
U.S. Pat. No. 6,339,210 to Hembree et al., assigned to the assignee of the present invention, describes a system for back bonding a semiconductor die to and removing the semiconductor die from, a die pad of a lead frame by way of a heat-activated adhesive that is cured by an imbedded heating circuit on the die pad. However, Hembree discloses attaching a die cover to the die pad, and does not disclose apparatus for installing, removing, and replacing a semiconductor die using a flip chip connection approach.
Accordingly, it would be advantageous to develop apparatuses and methods for removing and installing a flip chip configured or otherwise conductively bumped semiconductor die on a substrate that improves on the state of the art and eliminates some of the disadvantages thereof. Particularly, it would be advantageous to enable removal of individual components of a module comprising a plurality of individual semiconductor devices such as a memory module, by way of heating elements that melt or soften an electrically conductive material used in conductive bumps. In addition, it would be advantageous to enable individual semiconductor devices employing a flip chip or otherwise conductively bumped semiconductor die or semiconductor dice to be removed or installed by way a thermal supply circuit carried by either the semiconductor die or the substrate with which it is associated.